Sweetener for dry cleaners&#39; solvents



July 30, 1963 R. G. RIEDE 3,099,626

SWEETENER FOR DRY CLEANERS SOLVENTS Filed Dec. 51, 1958 I 2 Sheets-Sheet 1 COMPARISON OF HYDRATE-D CALCIUM SILICATE SWEETENER WITH OTHER DRYCLEANING SWEETENERS FATTY ACID REM OVAL HIGH FILTATION RATE DlA-roMAcsous EARTH MAGNESIUM 1 SILICATE ACID TYPE. Swans-raven NUMBER ACTIVATED Vees.

TABLE CARBON TYPE CJJWEETNER HYDRATED CALCIUM eILICATL sWE ETENER OJ l l l l l O 2 4- 6 I 8 IO NUMBER OF LOADS INVENTOR.

RAYMOND G. Rmoa ATTORNEY y 1963 R. G. RIEDE 3,099,626

SWEETENER FOR DRY CLEANERS SOLVENTS Filed Dec. 31, 1958 2 Sheets-Sheet 2 Fi 2. COMPARISON OF HYDRATED CALCIUM SILICATE SWEETENER WITH OTHER DRYCLEANING SWEETENERS 6 FILTER PRESSURE QFILTER ACTIVATED VEGETABLE INLET CARBON TYPE SWEETENER PRESSURE P5]: 4- MAGNESIUM gILICATE.

TYPE SWEETENER HYDRATED CALCIUM 2 u \cATE SWEETENER HIGH FILTRATION RATE Dm-roMAcEous EARTH o l l l O 2 4 6 8 IO NUMBER OF LOADS ACCELERATED LABORATORY DRYCLEANING DETERGENT TEST USING A ONE PERCENT CHARGED REMOVED PETROLEUM SOLVENT. DIATOMACEOUS EARTH /o PRECOAT AND 5WEETENER TO EACH 8 MAGNESIUM slucATE LOAD TYPE swEET- DETERGENT REMOVAL 6 ENER 4 HYDRATED CALCIUM SILICATE ENER INVENTOR. o RAYMOND G. RIEDE BY M EXPRESSED A5 C6 DETERGENT REMOVED PER GRAM SWEETENER: MAG. slL.=o.34 HYDRATED CALCIUM SILICAT SWEETENER=OJ6 ATTORNEY United States Patent U 3,099,626 SWEETENER FOR DRY CLEANERS SOLVENTS Raymond G. Riede, Martinsville, N.J., assignor to Johns- Manville Corporation, New York, N.Y., a corporation of New York Filed Dec. 31, 1958, Ser. No. 784,254 9 Claims. (Cl. 252-463) This invention relates to sweetening agents for dry cleaners solvents and more particularly to particulate hydrated calcium silicate dry cleaners solvent sweeteners.

Typical dry cleaning techniques include dissolving and/ or removing fatty acids, among other soil components from soiled garments with an organic solvent such as petroleum solvents, perchlorethylene, carbon tetrachloride, etc., containing soap or detergent-s. However, because excessive fatty acid concentration or content in dry cleaning media can result in undesirable odors, cause objectionable streaks and swales in garments being cleaned and increased drying time, their presence must be effectively controlled or removed. Of course all soluble soils, including fatty acids, may be completely removed from the solvent by distillation but this means of purifying the solvent in addition to being time-consuming, removes costly detergent as well as objectionable impurities or soil. Because of the high cost of typical dry cleaning detergents, among other reasons, many dry cleaners find it uneconomical or otherwise undesirable to regularly distill.

Accordingly, various dry cleaners solvent sweeteners have been proposed and/ or ut'lized in lieu of distillation. These sweeteners may be defined or described as materials which have the ability or capacity to remove soluble soils such as fatty acids from organic solvents by adsorption, saponification, or other chemical reaction. Typical sweeteners are categorized into two types: one type comprises absorbent materials such as activated carbon and activated clays which are highly effective in adsorbing soluble dyes but substantially ineffective in removing fatty acids, and the second type comprises alkali chemicals and magnesium silicates which neutralize or saponify fatty acids but are not adequate for controlling color, which if permitted to build up to excessive amounts can cause damaging colorizing of fabrics.

Products comprising synthetic magnesium silicates achieved extensive application in the removal \or control of fatty acids in dry cleaners solvents during the period when the typical procedure comprised the addition of fresh soap or detergent to each batch system of dry cleaning, which as the name implies, consists of adding a quantity of emulsified soap or detergent to each dry cleaning batch and filtering the same out with the accumulated soil upon completion of the batch. With the advent of the now almost universally adopted detergent charge system this type of sweetener has proved undesirable because of excessive detergent removal from the solvent. Moreover, the use of magnesium silicate type sweeteners often resulted in relatively high and undesirable filter pressures as well as not exhibiting entirely satisfactory or optimum acid removal properties. The detergent charge system, of course, consists of initially adding a charge of detergent which dissolves in the solvent and is not removed at the filter, hence maintaining the same charge throughout a series of washes or runs and filtering out only the soil upon completion of each batch from the filterable solvent and detergent solution.

It is a primary object of this invention to provide an improved and compatible dry cleaners solvent sweetener which is capable of controlling or maintaining a substantially uniform or constant fatty acids content (acid number) in typical dry cleaners solvents throughout a substantial number of cycles or loads. I,

It is a further object of this invention to provide an efficient and effective adsorbent for fatty acids which does not remove excessive amounts of soap or detergent from the system and does not impart high filter pressures.

It is a still further object of this invention to provide a calcium silicate sweetener for dry cleaners solvent which effectively stabilizes the fatty acids content (acid number) of dry cleaners solvents without appreciably increasing filter pressure or uneconomically removing soap or detergent froin the system.

It is a still further object of this invention to provide a sweetener for dry cleaners solvents which preferentially adsorbs the fatty acids soil content when utilized in a system containing a high acid soap or detergent and which retains the adsorbed acids thereby inhibiting a build-up of either fatty acids and/ or acid neutralization products, i.e., the non-volatile content of the cleaning solvent.

This invention will be more fully understood and further objects and advantages thereof will become apparent from the hereinafter detailed description and the drawings in which:

FIG. 1 is a graph showing a comparison of the fatty acids removal characteristics of the combination of this invention and conventional type sweeteners;

FIG. 2 is a graph showing a comparison of the filter pressures resulting from the use of the combination of this invention and the conventional type sweeteners; and

FIG. 3 is also a graph showing the relative soap or detergent removal characteristics of the combination of this invention and a conventional magnesium silicate type sweetener.

According to the present invention, the foregoing as well as other advantages are achieved by utilizing a hydrated calcium silicate of synthetic origin as a sweetener and/ or adsorbent for fatty acids soil in dry cleaners solvents. The hydrated calcium silicates of this invention eifectively reduce or control fatty acids concentrations (acid number) by maintaining an approximately constant acid concentration or level without exhibiting uneconomical or undesirable side effects such as detergent adsorption and high filter pressures, among other possible disadvantages, and they are simple to administer or utilize. For example, the particulate hydrated calcium silicate materials of this invention simply need be added or admixed with the acid soil contaminated dry cleaners solvent by dispersing the particulate material throughout the solvent at substantially any point or stage of a typical dry cleaning system.

The preferred hydrated calcium silicates for the practice of this invention are prepared by hydrothermal reaction of lime and a siliceous material such as diatomite. Further, it is also preferred that the hydrated calcium silicate comprise the calcium silicate composition identified in the art as calcium silicate hydrate I, a compound of variable compositions described in detail by Taylor, Journal of the Chemical Society No. 163 (1950). One method of preparing such a component is described in United States Letters Patent No. 1,574,363 to Calvert, but Calverts reaction may be materially facilitated and enhanced by reacting the lime and siliceous component at elevated temperatures and pressures, for example, from about atmospheric to 170 p.s.i.g. and F. to 375 F. Further, the preferred calcium silicate hydrate 1 compound comprises one hydrothermally prepared from lime and a siliceous material such as diatornaceous earth in a CaO/SiO mol ratio of about 0.5. Other calcium silicate compositions such, for example, as xonotlite and the hydrated calcium silicate composition described in United States patent application Serial No. 736,203, filed May 19, 1958, now United States Patent No. 2,966,441, will likewise suffic'e. It should be understood, however, that hydrated calcium silicates of different chemical compositions from that of the calcium silicate hydrate I product,

and/or those produced by other methods, for example, precipitated hydrated calcium silicate prepared by reacting solutions of calcium chloride and sodium silicate, but of equivalent quality, may be utilized in the practice of this invention.

The amount cf hydrated calcium silicate required to sweeten the solvent depends, of course, upon the capacity of the particular calcium silicate composition, the acid content of the solvent (which in turn depends upon the Weight or amount of clothes cleaned per unit of solvent and their soil condition) and, among other potentially influencing factors, the degree or extent of acid removal desired. For purposes of illustration rather than limitation, typical proportions for most normal systems may consist of about 1 pound of sweetener per 1000 gallons per hour filter capacity when added after precolating or about A; to /z pound per 100 pounds of soiled clothes when added with the clothes. Typically, however, varying conditions and systems necessitate experimentation to determine proportions for desired or optimum results. Moreover, many dry cleaners prefer to work with a moderate fatty acids concentration, for example, an acid number of about 0.2 or a maximum allowable number of 0.3, 'and it therefore may be desirable or necessary that the sweetener does not remove all of the acids present but maintains a constant concentration and prevents a build-up from exceeding a predetermined acid number. For these reasons, and because the acid build-up depends, among other factors, on the soil content of the clothes as well as the weight and/or amount of the same and number of runs or batches, it is not practical or feasible to arbitrarily delineate appropriate amounts of hydrated calcium silicate to effect solvent sweetening. In other words, many conditions or variables must be taken into consideration before it is possible to ascertain the proper proportions or quantities of hydrated calcium silicate to be utilized and even then it may take several test runs to achieve a desirable or maximum level of operation.

To increase the porosity of the cake which accumulates upon the filter, among other advantages, it is desirable and preferred to incorporate with said calcium silicates an efiicient filter aid medium. These filter aid media may 1 comprise substantially any typical filter laid such as diatomaceous earth, perlite, cellulosic or carbonaceous materials, etc., provided it is compatible with the balance of the system and does not adsorb desirable components from the same. filter aid media. Filter aids may comprise up to about 75% by weight of the mixture or combination of hydrated calcium silicate and filter aid medium. Normally, mechanical admixtures or combinations comprising about 30% of a filter aid medium and about 70% of a hydrothermally prepared hydrated calcium silicate are pre ferred, but the ratio of approximately equal parts by weight of filter aid and hydrated calcium silicate is pretferred when the latter is prepared by precipitation rather than hydrothermal reaction.

The following examples illustrate the relative characteristics of the dry cleaners solvent sweetener cf the present invention and those of several conventional type sweeteners. It to be understood that the specified operating conditions, techniques or the like are exemplary and are not to be construed to limit the invention to the particular components, proportions or other conditions specified in the hereinafter described examples.

The following test method is based upon a 1% detergent charged system in accordance with the present trend of the industry. An anionic detergent (R. R. Streets Formula 886) was utilized as the standard detergent and a distilled water addition (based on volume of solvent), in line with commercial practice, was also made to the charge solvent. The calcium silicate sweetener of the examples was a calcium silicate hydrate I compound 4 prepared by reacting diatomaceous silica and lime in a mol ratio of about 0.5 at 360 -F. for two hours.

The test procedure consisted of a 10 load accelerated cleaning cycle. A constant rate of filtration of 1 gal/sq. ft/min. was maintained throughout the run and solvent temperature was maintained at 75 F. The filter was preco-ated for each cycle with a diatonraceous earth filter aid in the amount of 0.1 lb. per sq. ft. of filter surface. Each load consisted of the addition of solvent soluble (color and fatty acids) and insoluble (ground rug dirt) soils, make up water and batch powder. The cleaning load consisted of la 15 minute break run and a 15 minute circulation through the filter. 'I'he sweeteners to be evaluated and compared were added to each load on the basis of a theoretical clothes load of 3 lbs. which the figure upon which the washers were designed. Batch addition was at the rate of 1 1b. of sweetener per 100 lbs. of clothes. After each load inlet filter pressure was recorded, and a sample of solvent filtrate was taken to determine soluble soil removal. Detergent concentration was determined before the run was started and after the tenth load.

The general opinion of the dry cleaning industry being that the best cleaning is not accomplished when the solvent is completely devoid of fatty acids, most cleaners prefer to work with a moderate buildup of fatty acid, but safely below generally accepted maximum allowable figure of 0.3 acid number. Accordingly, this test procedure was designed to carry an acid number of about 0.2 and oleic acid was added to the solvent before the start of each run to provide this value.

This test compares conventional commercial dry cleaners solvent sweeteners comprising respectively a magnesium silicate type sweetener and an activated vegetable carbon type sweetener with a hydrated calcium silicate type sweetener of this invention, and a high filtration rate diatomaceous earth filter aid (a product sold under the trademark Hyfio). The magnesium silicate, activated vegetable carbon, and calcium silicate sweeteners com- Diatomaceous earth is the preferred pared each comprised 30% by weight of diatomaceous earth filter aid and 70% of the respective sweeteners.

The comparative results of the foregoing testing procedures are set forth in the following tabulation:

Comparison of Hydrated Calcium Silicate Sweetener With Other Drycleanmg Sweeteners and a Filter Aid Test sweetener Hydrated Magne- Activated High filcal. sihslum siliveg. cartration cate type cate type bon type rate diatosweetener sweetener sweetener maceous earth Filter Pressure, p.s.i.:

Start of run 1. End of run.. 3. 5 Diflerence 2. 5 Acid Number:

tart of run 183 End of run. 191 Difierence..- 008 Acid number removal 078 Fatty acid removed as oleic,

liq. oz O63 Fatty acid removal, liq. oz.

oleic/lb. sweetener 2.1 Optical density (color):

Start of run 194 End of run .176 Difierence 082 Color removal, percent 32 Detergent removal, percent- 7. 1 Detergent removal, cc. de-

tergent/gram sweetener- 0. 274 Water removal, cc, total.-." 3

1 Not recorded.

The fatty acid removal capacities of the materials tested are set forth in the foregoing tabulation and plotted on the graph of FIG. 1. From the graph it is readily apparent that the acid number of the solvent is substantially stabilized with the hydrated calcium silicate sweetener.

Diatomaceous earth (H-yflo) being inert removes no fatty acids and when using its plotted capacity line as a reference it is apparent that both the magnesium silicate and activated vegetable carbon type sweeteners remove some fatty acid but that they are relatively ineflicient when compared to a calcium silicate type sweetener. Expressing fatty acids removal in liquid ounces (as oleic) removed per pound of test powder, the values for hydrated calcium silicate, magnesium silicate, activated vegetable carbon type sweeteners each combined with 30% diatomaceous earth filter aid respectively are 2.1, 0.7 and 0.8 liquid ounces of acid per pound of sweetener.

The respective filter pressures of diatomaceous earth (Hyfio) and calcium silicate, magnesium silicate and activated vegetable carbon type sweeteners, each including 30% diatomaceous earth filter aid, are plotted in FIG. 2 of the drawings. While the calcium silicate type sweetener causes more pressure than straight diatomaceous earth, pressure build-up is relatively low, and compared with the magnesium silicate, activated vegetable carbon type sweeteners, it is favorable. Both the magnesium silicate and activated vegetable carbon type sweeteners would cause considerably more pressure had they not been mixed with 30% of a diatomaceous earth filter aid medium.

Due to the high cost of deter-gents, which range in price from about $5 .00 to $11.00 per gallon, excessive detergent removal cannot be tolerated and is an important consideration in the utilization of a sweetener in the charge system. The 70% calcium silicate and activated vegetable carbon type sweetener and 30% diatomaceous earth mixtures each removed 7.1% of Streets Formula 886 detergent whereas the 70% magnesium silicate and 30% diatomaceous earth type sweetener mixture removed 11.6%. The foregoing tabulation lists detergent removal in cubic centimeters of deter-gent removed per gram of test sweetener. FIG. 3 of the drawings illustrates the relative amounts of detergent removed by a commercial type sweetener consisting of magnesium silicate and the preferred 70% hydrated calcium silicate-30% diatomaceous earth filter aid sweetener of this invention under like test conditions.

It will be understood that the details given are for the purposes of illustration, not restriction, and that variations within the spirit of this invention are intended to be included in the scope of the appended claims.

What I claim is:

1. In a process for dry cleaning soiled garments wherein an organic solvent medium is employed to remove soil from the garments, the method of sweetening, the fatty acid soil contaminated solvent medium which comprises controlling and stabilizing the fatty acid content of the solvent medium by preferentially adsorbing fatty acid from the medium with sweetener consisting essentially of particulate hydrated calcium silicate.

2. In a process for dry cleaning soiled garments wherein an organic solvent medium is employed in a system to remove soil from the garments, the method of sweetening the fatty acid soil contaminated solvent medium of the system which comprises dispersing throughout the solvent medium a combination consisting essentially of at least approximately 25% by weight of particulate hydrated calcium silicate with a filter aid selected from the group consisting of diatomaceous earth and perlite and mixtures thereof in amount up to approximately 75% by weight, and controlling and stabilizing the fatty acid content of the solvent medium by preferentially adsorbing fatty acid from the medium with the particulate hydrated calcium silicate, and removing the adsorbed fatty acid soil from the system by filtering the same.

3. In a process for dry cleaning soiled garments wherein an organic solvent medium is employed in a system to remove soil from the garments, the method of sweetening the fatty acid soil contaminated solvent medium of the system which comprises dispersing throughout the solvent medium approximately A to 1 pound per 100 pounds of soiled garments cleaned, of a combination consisting cssentially of about 70% by weight of particulate hydrated calcium silicate with about 30% by weight of filter aid selected from the group consisting of diatomaceous earth and penlite and mixtures thereof, and controlling and stabilizing the fatty acid content of the solvent medium by preferentially adsorbing fatty acid from the medium with the particulate hydrated calcium silicate, and removing the adsorbed fatty acid soil from the system by filtering the same.

4. In a process for dry cleaning soiled garments wherein an organic solvent medium is employed in a system to remove soil from the garments, the method of sweetening the fatty acid soil contaminated solvent medium of the system which comprises admixing with the solvent medium approximately to 1 pound per pounds of soiled garments cleaned, of sweetener consisting essentially of particulate hydrated calcium silicate produced by hydrothermal reaction of lime and silica, and controlling and stabilizing the fatty acid content of the solvent medium by preferentially adsorbing fatty acid from the medium with the particulate hydrated calcium silicate.

5. In a process for dry cleaning soiled garments wherein an orgainc solvent medium is employed in a system to remove soil from the garments, the method of sweetening the fatty acid soil contaminated solvent medium of the system which comprises admixing with the solvent medium a combination consisting essentially of at least approximately 25% by weight of particulate hydrated calcium silicate produced by hydrothermal reaction of lime and silica, with a filter aid selected from the group consisting of diatomaceous earth and perlite and mixtures thereof in amount up to approximately 75 by weight, and stabilizing the fatty acid content of the solvent medium by preferentially adsorbing fatty acid from the medium with the particulate hydrothermally produced hydrated calcium silicate, and removing the adsorbed fatty acid soil from the system by filtering the same.

6. In a process for dry cleaning soiled garments wherein an organic solvent medium is employed in a system to remove soil from the garments, the method of sweetening the fatty acid soil contaminated solvent medium of the system which comprises admixing with the solvent medium a combination consisting essentially of about 70% by weight of particulate hydrated calcium silicate produced by hydrothermal reaction of lime and silica, with about 30% by weight of filter aid selected from the group consisting of diatomaceous earth and perlite and mixtures thereof, and controlling and stabilizing the fatty acid content of the solvent medium by preferentially adsorbing fatty acid from the medium with the particulate hydrothermally produced hydrated calcium silicate, and removing the adsorbed fatty acid soil from the system by filtering the same.

7. In a process for dry cleaning soiled garments wherein an organic solvent medium is employed in a system to remove soil from the garments, the method of sweetening the fatty acid soil contaminated solvent medium of the system which comprises admixing with the solvent medium a combination consisting essentially of at least about 25 by weight of particulate hydrated calcium silicate produced by hydrothermal reaction of lime and siliceous material, with a filter aid selected from the group consisting of diatomaceous earth and perlite and mixture thereof in amount up to approximately 75 by weight, said combination being admixed with the solvent medium in proportions of approximately 1 pound per 1000 gallons of solvent, and controlling and stabilizing the fatty acid content of the solvent medium by preferentially adsorbing fatty acid from the medium with the particulate hydrothermally produced hydrated calcium silicate, and removing the adsorbed fatty acid soil from the system by filtering the same.

8. In a process for dry cleaning soiled garments wherein an organic solvent medium is employed in a system to remove soil from the garments, the method of sweeteni ng the 'fatty acid soil contaminated solvent medium of the system which comprises admixing With the solvent medium a combination consisting essentially of about 70% by weight of particulate hydrated calcium silicate produced by hydrothermal reaction of lime and siliceous material, with about 30% by Weight of filter aid selected from the group consisting of diatomaceous earth and perlite and mixtures thereof, said combination being added in amount of approximately 1 pound per 1000 gallons of solvent, and controlling and stabilizing the fatty acid content of the solvent medium by preferentially adsorbing fatty acid from the medium with the particulate hydrothermally produced hydrated calcium silicate, and removing the adsorbed fatty acid soil from the system by filtering the same.

9. In a process for dry cleaning soiled garments wherein an organic solvent medium including detergent is employed to remove soil from the garments, the method of sweetening the fatty acid soil contaminated solvent medium which comprises controlling and stabilizing the fatty acid content of the solvent medium by adsorbing fatty acid from the solvent medium preferentially over the detergent contents thereof with sweetener consisting essentially of particulate hydrothermally produced hydrated calcium silicate.

References Cited in the file of this patent UNITED STATES PATENTS 1,574,363 Calvert Feb. 23, 1926 1,851,808 Calvert Mar. 29, 1932 1,917,096 Chamberlin July 4, 1933 2,315,410 Simons et a1. Mar. 30, 1943 2,665,996 Kalousek Jan. 12, 1954 

1. IN A PROCESS FOR DRY CLEANING SOLID GEARMENTS WHEREIN AN ORGANIC SOLVENT MEDIUM IS EMPLOYED TO EMOVE SOIL FROM THE GARMENTS, THE METHOD OF SWEETENING, THE FATTY ACID SOIL CONTAMINATED SOLVENT MEDIUM WHICH COMPRISES CONTROLLING AND STABLIZING THE FATTY ACID CONTENT OF THE SOLVENT MEDIUM BY PREFERENTIALLY ADSORBING FATTY ACID FROM THE MEDIUM WITH SWEETENER CONSISTING ESSENTIALLY OF PARTICULATE HYDRATED CALCIUM SILICATE. 